If you have played MMO PvP at all over the years then you know how big of a problem CC has been to developers. There is nothing worse than losing control of your character. It makes you feel completely helpless and is one of the most frustrating things about PvP. How many of us have yelled in frustration as a rogue stun-locked us to death in WoW? How about getting feared and DPS’d down by a warlock? Or how about ‘sheeped’ by a mage while your healer was killed?
And that’s just WoW. If you played DAoC, you will never forget the mez and stun bombs. Not every CC is in the form of a stun, sleep or fear. In Warhammer my Ironbreaker had 3-4 knockbacks. Its not a normal type of CC but it is a CC and could be incredibly frustrating. I could keep players away from the healers at will, just by knocking them back constantly and God help them if there was a cliff or lava nearby because they would immediately be knocked over the cliff or into the lava. Warhammer also had the Magus, who could pull multiple characters into the center, where they could all be AoE’d down by a coordinated group.